Crystal structures of complexes of the small ribosomal subunit with tetracycline, edeine and IF3

The small ribosomal subunit is responsible for the decoding of genetic info rmation and plays a keg role in the initiation of protein synthesis. We ana lyzed by X-ray crystallography the structures of three different complexes of the small ribosomal subunit of Thermus thermophilus with the A-site inhi bitor tetracycline, the universal initiation inhibitor edeine and the C-ter minal domain of the translation initiation factor IF3, The crystal structur e analysis of the complex with tetracycline revealed the functionally impor tant site responsible for the blockage of the A-site, Five additional tetra cycline sites resolve most of the controversial biochemical data on the loc ation of tetracycline, The interaction of edeine with the small subunit ind icates its role in inhibiting initiation and shows its involvement with P-s ite tRNA, The location of the C-terminal domain of IF3, at the solvent side of the platform, sheds light on the formation of the initiation complex, a nd implies that the anti-association activity of IF3 is due to its influenc e on the conformational dynamics of the small ribosomal subunit.